Dissertation / PhD Thesis/Book

FZJ-2016-01737

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Emissions of Biogenic Volatile Organic Compounds and Ozone Balance under Future Climate Conditions

Wu, C. (Corresponding author)FZJ*

2016
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-121-7

Please use a persistent id in citations: http://hdl.handle.net/2128/10014

Abstract: Ozone (O$_{3}$) is a phytotoxic trace gas in the troposphere where it is photochemically produced from volatile organic compounds (VOCs) and nitrogen oxides (NO$_{x}$ = NO + NO$_{2}$). The dominant sink of O$_{3}$ in the air over areas with dense plant cover is dry deposition on plant surfaces. However, plants canalso contribute to photochemical O$_{3}$ formation because they emit biogenic VOCs (BVOCs). In this study, the role of vegetation for tropospheric ozone balance was investigated by consideringthe following processes: O$_{3}$ depletion by dry deposition on plant surfaces, O$_{3}$ depletion by gas phase reactions with plant emitted BVOCs, and photochemical O$_{3}$ production from BVOCs. Furthermore, drought and heat stress were applied to the plants, and possible impacts of these stresses on plant performance and on the tropospheric ozone balance were investigated. Dry deposition of O$_{3}$ was dominated by O$_{3}$ uptake through the plants stomata with negligible losses on cuticle and stem. For strong BVOC emitter, O$_{3}$ destruction by gas phase reactions with BVOCs wassignificant at low NO$_{x}$ conditions. Switching from low NOx to high NO$_{x}$ conditions led to O$_{3}$ production. A ratio of O$_{3}$ formation rates over BVOC loss rates was measured for $\alpha$-pinene as single BVOC and for BVOC mixtures emitted from real plants. For O$_{3}$ formation under BVOC limited conditions, this ratio was in the range of 2–3 ppb/ppb. The ratio of O$_{3}$ uptake/BVOC emission reflects the capability of aplant as a potential source of O$_{3}$, while NO$_{x}$ concentration and BVOC/NO$_{x}$ ratio determine whether the emitted BVOCs act as an additional sink or a source of O$_{3}$. O$_{3}$ uptake rates and BVOC emission rates are affected by environmental variables such as temperature, light intensity and stresses to plants. The impacts of them are different and thus the capability of a plant to be a source of O$_{3}$ is also affected by these variables. The focus of this work was the evaluation of the impact of drought and heat stress because future climate change will bring more and intense heat waves and elongated drought periods. With the application of moderate drought, the capability of a plant to be a source of O$_{3}$ increased; under conditions of severe drought the impact of plants in the O$_{3}$ balance decreased to almost zero. Heat stress also changes the capability of the plant to be a source of O$_{3}$. However, this change depends on the basic emission mechanisms of BVOCs and the severity of stress.

Note: RWTH Aachen, Diss., 2015

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2016

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Database coverage:

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